Microscope illuminator



Dec. 28, 1937.

J. R. BENFORD ET AL MICROSCOPE ILLUMINATOR Filed June 50, 1937 f: g I 32 7"44 I M 25 JAMES R.BENFORD LEON V. FOSTER 1N VENTORS ATTORNEYS Patented Dec. 28, 1937 nuirso stares 2,103,230 H monosoorn ILLUMINATOR= w James R. Benford, Rochester, and 'Leon'V. Foster,

Irondeq'uoit, N'. Y., assignors toBausc-lrsz'Lomb Optical Company, Rochester, N. Y., a corpora- I tion of New York Application June 30, 1037, Serial No. 151,200

3 Claims; (01. .44

be rapidly and easily changed from av bright field to a dark field illurninator. Another object is to provide a selective bright or dark field illuminator for opaque objects. A further object is to 0 provide such an iluminatorhaving at its upper end means for attaching it to the body tube of a microscope and at its lower end, meansfor detachably holding a condenser and objective. These and other objects and advantages reside in certain novel features or" construction, ar-

rangement and combination of parts as will hereinafter be more fully set forth and. pointed out in the appended claims. 7

Referring to the drawing:

Fig. l is a front elevation of illuminator. I

2 a vertical. section thereof showing the arrangement for dark field illumination.

our improved Fig. 3 is a vertical section thereof showing the arrangement for bright field illumination.

Fig. l is a section taken on line eof Fig. 2.

Fig. 5 is a vertical section of the condenser mount showing a reflecting condenserr In the preferred embodiment of our invention, as illustrated in the drawing, the illuminator consists of a casing it having a threaded ring H rctatably secured on the upper end thereof by a collar 12 for securing the casing It to the body tube 53 of a microscope. The microscope s is conventional and hence only the body tube I3 is shown.

The casing l8 has an opening 54 in one side and an extension 15 on that side of the casing carries a lamp housing iii. A prefocused lamp to H and condensing system it! direct a concentrated beam of light into the casing it. The extension 55 is formed with a slot is between the lamp housing 1% and easing it to receive the usual filters, polarizers or the like, not 25 shown.

A ring Ell is secured at the bottom end of the casing is by a set screw 2! and has a plurality of inwardly inclined projections 22. A second casing 23 has a similar number of outwardly'in- 5i) clined lugs 26 for engaging the projections 22 and securing the casing 23 on the casing l3.

Fig. 4 shows the lugs 24 and projections 22 in position for attachment or withdrawal of the second casing 23. Fastened in the casing 23 by means of a ring 25, is a condenser 26 provided with a central aperture 21 within which. a metal bushing, 28 is fixedbymeans. of a collar 29.] The objective 331s sli'dablewithin the bushing. 38 and is provided with a shoulder 31 which. engagesthe bushing- 28. and positions the objective so that it 5-;

is pariocalwith the condenser 26. The objective 35]- is,; (if-course, positioned so that it is coaxial with the microscope; bodyv tube I 3l V Fig.- -5 shows. the reflecting: type of condenser.

In this form, "the condenser is made asari an- 10 i nular ring of glass 32-havi'ng a reflecting. surface 33. V The bushing and-bushing mountare" identical with those of the len s 26Tandlthe two condenser casings are interchangeable, the an ticular condenser tobe used depending-[upon 15 the objective required. M

A cylinder or housing 13 i is nanny mounted within the casing It! for rotation about the opti cal axis of the microscope. Within this housing M -is fixed a silvered-refiector 35 which isQin 0 alignment with the window 35land is inclined "so as to direct the light beam. from. the lamp '1! downwardly to the condenser 23. Thefreflector 35- is providedwith' a. central'.v aperture}?! in alignment with the obj ctive 3llfso thattheimage forming rays from the objective aomay pass up into the body tube l3 to the'microscope observation system, not shown. I

A tubular support 38 open at both top and I bottom is threaded in the top of the cylinder or housing 34 and extends downward through the opening 31 in the reflector 35. Within this support 38, a semi-reflecting transparent plate 39 is secured by a cylindrical cell 43.. The plate 33 is mounted at an angle equal and opposite to the angle of inclination of the reflector 35. I A cell t! carrying a lens 42 is threaded in a second window 43 in the cylinder 34 opposite the window 35. This lens 42, together with the condensing system i8, serves to focus the condenser I8 virtually in the image plane of the objective 30.

The casing in is provided with an arcuate slot 44 through which extends an operating handle ltlsecured to the cylinder or'housing 34. The 45 slot 44 isof such length that moving the handle it from one extreme position to the other, presents either the window 36 orthe window 43 to V the light beam. i

Fig. 2shows the cylinder 34 in the position for 7 dark field illumination. In this position of the casing 34, the light from the illuminating system is reflected downward in a hollow cylinder by the reflector 35 to the condenser 26', thus giving dark field illumination. For bright field ilr lumination, the handle 45 is moved through 180 degrees so that the cylinder 34 takes the position shown in Fig. 3. The light from the lamp I l is condensed by the condensing system l8 and the lens 42 focuses the condenser l8 virtually at the same distance from the objective 30 as the image plane so that the objective 3!] focuses the evenly illuminated condenser I8 at its own object plane.

From the foregoing, it will be apparent that we are able to attain the objects of our invention and provide a vertical illuminator which can be readily and rapidly changed froma dark field to a bright field illuminator. Various modifications can, of course, be made without departing from the spirit of our invention or the scope of the appended claims:

We claim:

- 1. An illuminator for attachment to the body 7 tube of a microscope, said illuminator comprising a casing having means for attaching it'to said body tube, a second casing secured at the lower end of the first casing, a light condensing element having a central aperture secured in said second casing, an objective mounted in said aperture in alignment with said body tube, a housing rotatably mounted in said first casing above said second casing, an inclined annular reflector mounted in said housing in alignment with said condensing element, a semi-reflecting element mounted in said housing in alignment with said objective at an inclination opposite to that of said annular reflector, said casing having an opening in one side thereof to admit light to said housing and means for rotating said housing to present selectively said annular reflector or said semi-reflecting elementto the opening in said casing.

2. A microscope illuminating system for selective bright field or dark field illumination, comprising a casing havingmeans for attaching it to the body tube of a microscope, a second casing secured to the first casing, a transparent condensing element having a central aperture therethrough secured in said second casing,v

means carried by said element for mounting a microscope objective in axial alignment with said body tube, means for directing a beam of light into said'first casing from one side,

a cylinder rotatably mounted within said first casing with its axis substantially coincident with the optical axis of the microscope, an inclined reflector having a central aperture therethrough mounted in said cylinder to direct said beam of light to said condensing element, a transparent reflector mounted in said cylinder in alignment with said objective, the transparent reflector being mounted at an angle equal and opposite to that of the inclined reflector, and means for rotating said cylinder in said casing to selectively present one or the other of said reflectors to said light beam.

3. A microscope illuminating system for selective bright field or dark field illumination, comprising a casing having means for'attaching it to the body tube of a microscope, a second casing secured to the first. casing, a transparent condensing element having a central aperture therethrough secured in said second casing,. means carried by said element for mounting a microscope objective in axial alignment with said body tube, means for directing a beam of light. into said first casing from one side, a cylinder ro-- tatably mounted within said first casing with its axis substantially coincident with the optical axis of the microscope, an inclined reflector having a central aperture therethrough mounted in said cylinder to direct said beam of light to said condensing element, a transparent reflector mounted in said cylinder in alignment with said objective, the transparent reflector being mounted at an angle equal and opposite to that of the inclined reflector, a lens mounted-in said cylinder in fixed alignment with said transparent reflector for focusing the light beam in the image plane of said objective, and means for rotating said cylinder in said casing to selectively present one or the other of said reflectors to said light beam.

JAMES R. BENFORD. LEON V. FOSTER. 

